This invention relates to perforate metal sheets and to the method of producing the same.
Present day problems of control of boundary layers in high velocity gas flow, temperature control of normally severely heated parts and the like are being met increasingly by the use of porous fused metal particle layers, as described in U.S. Pat. No. 2,554,343. In general, considerable difficulty has been encountered in providing such products to meet the critical factors of close control of uniformity in the size and shape of the pores and in tensile strength of the material.
It has been suggested that perforate sheet material having a myriad of uniformly and precisely dimensioned pores formed therein be employed. The preparation of these materials has met with difficulties.
One method of preparing such material is to drill holes in a metallic sheet in the required pattern and size. This is expensive and quite difficult to do as the pores must be set at close centers and there is a physical limit to how small the pores can be drilled.
Other methods involve fusing together the cross-over points of the mesh and then rolling the diffused mesh into a flat sheet wherein the pores cross-section size is reduced, and the material weakened. This process requires the use of heavy and expensive equipment for the rolling, especially for the wide sheets of material required for noise attenuation applications.